In the above-identified patent, as well as in application Ser. No. 366,864 filed by us jointly with Raimondo Paletto on June 4, 1973, and now abandoned, there has been disclosed a modular unit comprising two sets of conductor strips which are punched from a coherent metal foil and which, in an intermediate state of production, are interconnected by narrow bridges to be subsequently severed so as to insulate the strips from one another. A metal bar or block has a raised central portion constituting a platform which carries a silicon chip with integrated circuitry whose terminals are soldered to the extremities of the several conductor strips converging at that semiconductor. Thereafter the silicon chip and the adjoining parts of the foil are encased in a resinous body which surrounds the periphery of the metal block but leaves its underside exposed and flush with the lower face of that body.
IN THE MOLDING OF SUCH A UNIT IT IS SOMETIMES DIFFICULT TO AVOID THE INTRUSION OF PLASTIC MATERIAL BETWEEN THE EXPOSED BLOCK SURFACE AND THE ADJOINING MOLD HALF. It therefore becomes necessary to subject that block surface to a separate cleaning operation after the molding step. An alternative solution resides in temporarily but firmly fastening the block to the adjoining mold half and releasing it from the mold only after the hardening of the resin; this procedure is cumbersome, especially when it is desired to imbed more than one heat-dissipating member of this description in such a body.